Exercise step for aerobic exercise



FIG. 1 is a front right perspective view illustrating an exercise step for aerobic exercise showing my new design;

FIG. 2 is a rear left side elevational view thereof, the broken line showing of the leg is for illustrative purposes only, and forms no part of the claimed design;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for an exercise step for aerobic exercise, as shown and described. 